Pin grid array socket with reinforcement plate

ABSTRACT

A socket for a PGA package can maintain high reliability of connecting condition for a long period. The socket is constructed by mounting a reinforcement plate formed with a metal plate or the like at the position where the cam member contacts the slide plate so that the slide plate, which is formed of an insulative materials such as plastic or the like, will not be deformed upon exertion of a reaction force from a plurality of lead pins of a PGA package.

FIELD OF THE INVENTION

[0001] The present invention relates to a socket for pin grid array(“PGA”) package for connecting a PGA package, and in particular to a PGAsocket with a wear resistance plate used to extend the life of the PGAsocket.

BACKGROUND OF THE INVENTION

[0002] Conventional PGA sockets comprise a base housing having aplurality of terminals arranged in the form of grid, and a slide platehaving a corresponding plurality of through holes arranged in the sameform of grid as the base housing. The slide plate is placed on the basehousing, and the slide plate moves between an open position, in whichthe lead pins of the PGA package can be inserted in the through holes toreach the terminal mounts with an insertion force of zero or close tozero, and a locking position, in which the inserted lead pins are put inengagement with the terminals.

[0003] A cam member is provided along the rear edge of the base housing,which when activated, moves the slide plate between the open and lockedposition. In one embodiment, the cam member comprises a cam shaft thatis rotated by means of an operation handle provided along the sideportion of the socket (for example, see Japanese Unexamined PatentPublication No. Heisei 7-142134). Alternatively, the cam member isprovided in a direction extending through the base housing and the slideplate. By rotating the cam member by means of a driver or the like, thehandle is eliminated.

[0004] In the construction where the cam member is provided in anorientation extending through the base housing and the slide plate, thecam member is biased against the slide plate as the slide plate movesfrom an open to a locked position. In the condition where the lead pinsand the terminals are placed for engagement with each other (the lockedposition), a reaction force by a resilient force of the lead pin acts onthe cam member. The reaction force acting between the metallic cammember and the insulative slide plate, such as plastic or the like,contacting the cam member becomes greater as the number of lead pinsincrease. By this force, the portion of the slide plate which is incontact with the cam member can become deformed due to the fact that theinsulative slide plate is more flexible that the cam member. Thisdeformation can result in a convex deformation in the slide plate thatcan cause a degradation in the reliability of the PGA socket. Thisdeformation can be amplified in those situations where the PGA packagesare exchanged numerous times due to the large number of times that thePGA socket must be actuated between its open and locked positions.

SUMMARY OF THE INVENTION

[0005] The present invention has been worked out in view of theshortcoming set forth above. It is therefore an object of the presentinvention to provide a socket for a PGA package which can maintain highreliability of connecting condition for a long period.

[0006] The present invention is constructed by mounting a reinforcementplate formed with a metal plate or the like at the location where thecam member contacts the slide plate so that the slide plate will not bedeformed upon exertion of a reaction force from the plurality of leadpins of a pin grid array package. Rather that the reaction force beingdirected to the insulative slide plate, the reaction force is receivedby the reinforcement plate. This prevents the concaving deformation onthe slide plate. Thus, a highly reliable connection between the leadpins of the PGA package and the terminals of the base housing can beachieved. Furthermore, the life of the socket is extended.

[0007] The slide plate may be formed of an insulative synthetic resin,the reinforcement plate mounted on the straight edge may be formed witha metal plate, and the cam member may be formed of a metal. Thereinforcement plate may be formed in a cross-sectionally channel shapedconfiguration and may be mounted by clamping the reinforcement plate toa portion of the straight edge of the slide plate. The reinforcementplate may be formed into a cross-sectionally channel-shapedconfiguration having an upper wall and a lower wall clamping the slideplate. The lower wall of the reinforcement plate may have a lengthshorter than the upper plate.

[0008] In the preferred construction, a length of the reinforcementplate in a direction along the straight edge may be shorter than alength of the straight edge for slidably mounting the reinforcementplate along the straight edge. Also, a length of the reinforcement platemay be set at a length to permit engagement with the contact surface ofthe cam member even when the reinforcement plate is stopped withabutting the end of the reinforcement plate with the end of the straightedge.

[0009] In another embodiment, the reinforcement plate is mounted to theslide plate in such a manner that the reinforcement plate is moveablealong the straight edge of the slide plate.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0010] The features of this invention which are believed to be novel areset forth with particularity in the appended claims. The invention,together with its objects and the advantages thereof, may be bestunderstood by reference to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals identify like elements in the figures and in which:

[0011]FIG. 1 is a plan view of the preferred embodiment of a socket fora PGA package according to the present invention;

[0012]FIG. 2 is a longitudinal section of the preferred embodiment ofthe socket for the PGA package;

[0013]FIG. 3 is an enlarged section of a com member engaging portion ofthe socket for the PGA package taken along line 3-3 of FIG. 1;

[0014]FIG. 4 is a front elevation of the cam member;

[0015]FIG. 5 is a bottom view of the cam member;

[0016]FIG. 6 is a plan view of the cam member;

[0017]FIG. 7 is a side elevation of the cam member;

[0018]FIG. 8 is a back elevation of the cam member;

[0019]FIG. 9 is a section of the cam member;

[0020]FIG. 10 is a plan view of the socket showing a condition where theslide plate is slid by rotating the cam member over 180 degrees from thecondition shown in FIG. 1;

[0021]FIG. 11 is a perspective view of a reinforcement plate;

[0022]FIG. 12 is a perspective of another embodiment of thereinforcement plate; and

[0023]FIG. 13 is an illustration of a mounting structure of a furtherembodiment of the reinforcement plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] While the invention may be susceptible to embodiment in differentforms, there is shown in the drawings, and herein will be described indetail, specific embodiments with the understanding that the presentdisclosure is to be considered an exemplification of the principles ofthe invention, and is not intended to limit the invention to that asillustrated and described herein. It will be obvious, however, to thoseskilled in the art that the present invention may be practiced withoutthese specific details. In other instance, well-known structure are notshown in detail in order to avoid unnecessary obscurity of the presentinvention.

[0025]FIGS. 1 and 2 show the preferred embodiment of a socket 10 for aPGA package. The socket 10 for the PGA package is constructed with asubstantially quadrangular base housing 20 and a substantiallyquadrangular slide plate 40 provided on an upper side of the basehousing 20. In the base housing 20, a plurality of terminals 21 shown inFIG. 2 are loaded in grid array form. Tails 22 extending from theterminals 21 are arrayed on the bottom surface of the base housing 20.Engaging portion of the terminal 21 is opened at the upper surface forreceiving a lead pin of the PGA package (not shown).

[0026] The slide plate 40 is formed with through holes 41 in a gridarray form corresponding to the terminals 21 on the side of the basehousing 20. Sectionally L-shaped side plates 42 depending from both sideedges of the slide plate 40 engage with guide ridge 23 formed on theside surface of the base housing 20 in a holding manner. Thus, the slideplate 40 is slidable only in a direction along the side edge (up anddown direction in FIG. 1).

[0027] As shown in FIG. 3 (which is a section taken along line 3-3 ofFIG. 1), the slide mechanism of the slide plate 40 is constructed with acam member 60 provided rotatable at one end of the base housing 20(which cam member is rotatable about an axis extending perpendicular tothe sheet surface of FIG. 1), and an opening portion 44 formed in an endportion 43 extending from one end of the slide plate 40. A cam portion61 of the cam member 60 extends upwardly through the opening portion 44.A cam surface 62 opposes the opening edge 45.

[0028] The cam member 60 is a cylindrical one piece member having aconstruction shown in FIGS. 4 to 9. An external upper portion forms acam portion 61. A bearing hole 63 is formed eccentrically relative tothe cam portion 61 inside from the bottom surface side. By fitting thebearing hole 63 on a pivot axle 24 provided on the base housing 20, thecam member 60 is rotatable about the pivot axle 24. The pivot axle 24extends beyond the upper surface of the slide plate 40 through theopening portion 44 of the slide plate 40. The bearing hole 63 is fittedover the entire length of the pivot axle 24.

[0029] A pair of engaging legs 64 are extended downwardly along a centeraxis of the bearing hole 63. The engaging legs 64 extend beyond thebottom surface of the cam member 60. Outwardly extending hooks 65 areformed at the distal ends of the engaging legs 64. A pair of engaginglegs 64 are inserted into the pivot axle 24 for placing the hookportions 65 within a recess 25 formed in the bottom of the base housing20. The hooks 65 engage the cam member 60 to the base housing 20.

[0030] As shown in FIGS. 4 to 9, the cam member 60 is formed with acontact surface 62 a on the cam surface 62 formed in the cam portion 61.The contact surface 62 a is formed at a portion most distant from thecenter of the bearing hole 63, namely at the position where a liftingamount of the cam surface 62 becomes maximum. The contact surface 62 ais formed over the entire length in the longitudinal direction of thecam portion 61. Two indicators 66 are radially projected from the upperportion of the cam portion 61, in a direction perpendicular to thecontact surface 62 a as viewed from the center of the bearing hole 63.

[0031] On the upper surface of the cam portion 61, namely the uppersurface of the cam member 60, a hexagonal recess 67 is formed so thatthe cam member 60 may be directly driven to rotate by means of arotating tool formed with a hexagonal rod. The hexagonal recess 67provided on the upper surface of the cam member 60 is provided at thecenter of the upper surface thereof As can be seen from FIG. 3, thecenter is offset from the center of the pivot axle 24. By this, when thecam member 60 is rotated about the pivot axle 24, the contact surface 62a of the cam surface 62 biases the slide plate 40 toward the left asviewed in FIG. 3.

[0032] The opening portion 44 formed in the end piece 43 of the slideplate 40 is formed into a rounded quadrangular shape and is constructedwith straight edges 45 a and 45 b mutually opposing in back and forthdirection and arc-shaped edges 45 c and 45 d opposing in left and rightdirection. The distance between the straight edges 45 a and 45 b issubstantially equal to the diameter of the cam portion 61 of the cammember 60. The arc-shaped edges 45 c and 45 d are opposed in a left andright direction with a distance greater than the distance between thestraight edges 45 a and 45 b.

[0033] A stopper 46 is provided on the outside of one of the sides ofthe opening portion 44, to engage with the two indicators 66 in a mannerthat the two indicators 66 holds the socket in an open position (theposition where the PGA package is not loaded on the socket, asillustrated in FIG. 1).

[0034] In the embodiment shown in FIG. 3, a reinforcement plate 30formed of a metal plate is mounted on the straight edge 45 a of theslide plate 40. As shown in FIG. 11, the reinforcement plate 30 isformed by bending the metal plate into sectionally channel-shapedconfiguration and is mounted on the opening edge 45 of the slide plate40 in snap-in manner. The reinforcement plate 30 is slidable along thestraight edge 45 a. The length L1 of the reinforcement plate 30 in adirection along the straight edge 45 a is shorter than the length of thestraight edge 45 a and is set so that the contact surface 62 a of thecam member 60 does not contact directly to the slide plate 40 even atthe position where the straight edge 45 a is not in contact withreinforcement plate 30.

[0035]FIGS. 1 and 3 shows the slide plate 40 in an open position, i.e.,the pins of the PGA package are enabled for insertion up to the engagingportions of the terminals 21 of the base housing 20 with an insertionforce of zero or close to zero. The two indicators 66 of the cam member60 engage with the stopper 46 and the contact surface 62 a formed on thecam surface 62 is engaged with the straight edge 45 b of the openingportion 44.

[0036] Engagement between the contact surface 62 a of the cam surface 62and the straight edge 45 b of the opening edge 45 may provide a tactilefeel to an operator at the same time of engagement between the indicator66 and the stopper 46 when the cam member 60 is rotated up to thecondition shown in FIG. 1 in counterclockwise direction. Also,engagement between the contact surface 62 a of the cam surface 62 andthe straight edge 45 b of the opening edge 45 also serves for preventingunintentional clockwise rotation of the cam member 60 by vibration orother causes. Since the indicator 66 and the stopper 46 are engaged,rotation of the cam member 60 in counterclockwise direction can also beprevented. In this condition, the PGA package to be connected is mountedon the slide plate 40 with the lead pins oriented downwardly. The leadpins can be inserted up to the engaging portion of the terminals 21 ofthe base housing 20 via through holes 41 of the slide plate with aninsertion force of zero or close to zero.

[0037] By rotating the cam member 60 after mounting the PGA package inthe PGA socket in a clockwise direction of approximately 180 degrees,connection between the PGA package and the PGA socket is completed, asshown in FIG. 10. By rotation of the cam member 60 (direction of arrow Ain FIG. 10), the slide plate 40 is slid downwardly (direction of arrow Bin FIG. 10) along the base housing 20 to move the lead pins insertedinto the through holes 41 to engage with respective terminals 21.

[0038] By this, the contact surface 62 a of the cam surface 62 engageswith straight edge 45 a via the reinforcement plate 30. When the leadpins are moved to the position engaging with the terminals 21, resilientforce of the lead pins acts on the slide plate 40 as a reaction force.The reaction force becomes greater in the PGA package as the number ofterminals increase. When the reaction force directly acts on the slideplate 40 from the cam member 60, the slide plate 40 formed of insulativeresin material, such as plastic or the like, can cause concavingdeformation. However, in the embodiment of the present application, thereaction force is directed to the reinforcement plate 30. Therefore, thestraight edge 45 a of the slide plate 40 will never be deformed.

[0039] Furthermore, when the contact surface 62 a of the cam surface 62and the straight edge 45 a of the opening edge 45 engage via thereinforcement plate 30, the engaging condition is maintained by thereaction force. Therefore, unintentional rotation of the cam member inthe counterclockwise direction can be prevented. Accordingly, engagementbetween the lead pins and the terminals 21 will be maintained.Furthermore, with the reaction force being directed to the reinforcementplate 30, the slide plate 40 will never be deformed even when the cammember 60 is rotated many times. Therefore, reliability of terminalconnection can be maintained for a long period to extend the life of thesocket.

[0040] In the rotating operation of the cam member 60, because of astructure to engage the bearing hole 63 of the cam member 60 with thepivot axle 24 of the base housing 20 in relatively long range close tothe entire length of the cam member 60, the cam member 60 will nevertilt, thereby allowing for smooth rotational operation. Additionally,sliding of the slide plate 40 can be assured in the predetermineddistance. The engaging feature of the cam member 60 prevents the cammember 60 from separating from the base housing as a result of thesliding resistance of the slide plate 40.

[0041] In the shown embodiment set forth above, as shown in FIG. 11, thereinforcement plate 30 is constructed with equal length (lengths of thewalls 30 a and 30 b extending in a direction away from base wall 30 d)of upper wall 30 a and the lower wall 30 b to have a channel shapedcross-section. However, the present invention should not be limited tothe particular construction of the shown embodiment. For instance, thelength of the lower wall 30 b′ can be shorter as shown in FIG. 12. Withthe construction shown in FIG. 12, mounting of the reinforcement plate30 on the slide plate 40 by snap-in can be facilitated to contribute forlowing of assembling cost.

[0042] As set forth above, the reinforcement plate 30 is slidablymounted on the slide plate 40. When the PGA package is firmly loaded onthe socket by rotating the cam member 60, a large force is createdbetween the cam member 60 and the reinforcement plate 30. At this time,if the reinforcement plate 30 is immovably fixed on the slide plate 40,it becomes difficult to rotate the cam member 60 to the final position.However, in the shown embodiment, since the reinforcement plate 30 ismovable along the straight edge 45 a, the cam member 60 can easilyrotate to the final position to contact the contact surface 62 a to thestraight edge 45 a to achieve good loading ability of the PGA package tothe socket.

[0043] For improvement of loading ability of the PGA package on thesocket 10 and for facilitating assembling of the reinforcement plate 30upon assembling the socket, a projection 30 c is provided on the lowersurface of the upper wall 30 a of the reinforcement plate 30.Additionally, a recessed portion 40 a, having wider area than theprojection 30 c, is formed on the slide plate 40 at the positionengaging the projection 30 c, as shown in FIG. 13. When thereinforcement plate 30 is mounted on the slide plate 40 by snap-in orother means, the projection 30 c enters the recessed portion 40 a andthe reinforcement plate 30 will be retained by the slide plate 40 duringinsertion of the PGA package into the socket 10. Furthermore, therecessed portion 40 a is sized to assure movement of the reinforcementplate 30 so that loading of the PGA package to the socket 10 can occur.

[0044] Although particular embodiments of the invention have beendescribed in detail for purposes of illustration, various modificationsand enhancements may be made without departing from the spirit and scopeof the invention. Therefore, the present invention should not beunderstood as limited to the specific embodiment set out above but toinclude all possible embodiments which can be embodied within a scopeencompassed and equivalents thereof Accordingly, the invention is not tobe limited except as by the appended claims.

1. A PGA socket, comprising: a base housing; a slide plate placed on anupper surface of the base housing, the slide plate being slidablebetween an open position and a locked position; a cam member rotatablysupported on the base housing, the cam member including a cam surfaceextending through an opening formed in the slide plate, the openingincluding an edge; and a reinforcement plate mounted on a straight edgeof the opening edge engaging with a contact surface formed on the camsurface.
 2. The PGA socket of claim 1, wherein the reinforcement plateengages the contact surface of the cam member when the slide plate is inthe locked position.
 3. The PGA socket of claim 1, wherein the slideplate is formed of an insulative synthetic resin, the reinforcementplate mounted on the straight edge is formed with a metal plate, and thecam member is formed of a metal.
 4. The PGA socket of claim 1, whereinthe slide plate includes a base wall and two side walls extendingoutwardly from the base wall.
 5. The PGA socket of claim 4, wherein oneof the side walls includes a projection that is received in a recess onthe base housing.
 6. The PGA socket of claim 1, wherein the length ofthe reinforcement plate is less than the length of the opening edge. 7.The PGA socket of claim 5, wherein one of the side walls is shorter thanthe other side wall in a direction extending outwardly from the basewall.
 8. The PGA socket of claim 1, wherein the length of thereinforcement plate is set at a length to permit engagement with thecontact surface of the cam member.
 9. The PGA socket of claim 1, whereinthe base housing include a stopper and the cam member includes at leastone indicator that makes contact with the stopper.
 10. The PGA socket ofclaim 1, wherein the cam member is mounted on a pivot axle.
 11. The PGAsocket of claim 5, wherein the recess in the housing is larger than theprotrusion, therefore allowing limited movement of the reinforcementplate.
 12. A socket for a pin grid array comprising: a base housingloaded a plurality of terminals in grid array form; a slide plate formedwith through holes in a grid array form corresponding to respectiveterminals with stacking on upper side of the base housing, the slideplate being slidable between a position where lead pins of the pin gridarray can be inserted up to engaging portions of the terminals and aposition where the inserted lead pins engage with the terminals; a cammember rotatably supported on the base housing and having a cam portionopposing a can surface thereof with en opening edge through an openingportion formed in the slide plate; and a reinforcement plate mounted ona straight edge of the opening edge engaging with a contact surfaceformed on the cam surface, when the slide plate is slid to the positionwhere the lead pins engage with the terminals.
 13. A socket for a pingrid array as set forth in claim 12, wherein the slide plate is formedof an insulative synthetic resin, the reinforcement plate mounted on thestraight edge is formed with a metal plate, and the cam member is formedof a metal.
 14. A socket for a pin grid array as set forth in claim 12,wherein the reinforcement plate is formed in cross-sectionally channelshaped configuration and is mounted on the straight edge of the slideplate.
 15. A socket for a pin grid array as set forth in claim 12,wherein the reinforcement plate is formed into cross-sectionallychannel-shaped configuration having a base wall, an upper wall and alower wall, the lower wall has a length shorter than the upper plate ina direction extending outwardly from the base wall.
 16. A socket for apin grid array as set forth in claim 12, wherein a length of thereinforcement plate is set at a length to permit engagement with thecontact surface of the cam member.
 17. A socket for a pin grid array asset forth in claim 12, wherein the base housing include a stopper andthe cam member includes at least one indicator that makes contact withthe stopper.
 18. A socket for a pin grid array as set forth in claim 12,wherein the cam member is mounted on a pivot axle.
 19. A socket for apin grid array as set forth in claim 15, wherein one of the upper andlower walls includes a projection that is received in a recess on thebase housing.
 20. A socket for a pin grid array as set forth in claim19, wherein the recess in the housing is larger than the protrusion,therefore allowing limited movement of the reinforcement plate.